M.Sc Thesis

M.Sc StudentFiliba Eytan
SubjectTransient Dynamics and Tradeoffs: Heterogeneous Populations
in a Competitive Changing Environment
DepartmentDepartment of Chemical Engineering
Supervisors PROF. Naama Brenner
PROF. Daniel Lewin
Full Thesis textFull thesis text - English Version


Organisms, even if deep in the ocean or under the ground, face variations in the environment they live in all the time. These variations may be expected and planned for in advance such as the changing of seasons or may take place suddenly, in which case they pose an existential danger to the organisms. To endure in such disagreeable surroundings, organisms are equipped with a number of survival tactics with different levels of sophistication.

One of these strategies is maintaining a heterogeneous population consisting of a number of phenotypes, however little is known about the precise conditions where this strategy will be advantageous. Although theoretical work exists for open systems with no competition for resources, this kind of environment constitute a major simplification. In the present work, a simple model system for a competitive environment, the chemostat, is used to study the relationship between varying environments and growth strategies in a proliferating cell population. Qualitative and quantitative conclusions regarding the dynamics of the classic two species takeover problem are derived. Dynamic heterogeneity is then evaluated as a survival strategy in the presence of varying environments using these results. It is shown that the analytical expressions derived from the different scenarios, can help quantitatively understand in which conditions heterogeneity is the optimal growth strategy for fluctuating environments.